I always go to the Dam with the missus and we always get an apartment or houseboat. Best experience was waking up on Xmas morning to snow covered ducks swimming past your bedroom window, with armadas of little boats full of amsterdammers waving at passers by. Houseboats rock.
An apartment or houseboat may cost more but you'll make up for it by being able to cook your own meals or snacks, and you don't feel the urge to spend day and night in coffeeshops buying overpriced hot chocolates and coffees. You also don't have the paranoia about walking back into a hotel trollied or making noisy lurve
Only downside to a houseboat is they're all strictly no smoking indoors, but they all have large opening windows

Just google amsterdam houseboat and theres tons of sites. I used to spend hours just looking at all the cool places to stay, but I love planning a holiday.
Here's some pics from xmas 05